That's how CNN was portraying it today and seems logical. I wonder though if Kyle was in contact with mental health professionals or decided this would be a good idea on his own.

Edit: OK so watching AC360, they were saying the shooter said to his sister, "I traded my soul for a new truck." So maybe it wasn't about exposure therapy and more just you're one of us therapy. Maybe it wasn't shooting that flipped the guys switch but something one of the victims said or the guy was jealous or something.